D7000 Technical Lens Question

bullitt411

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I'm not sure if this is the right place to post this, but I was looking for some help with a problem I'm having. I own a D7000 which has been functioning properly since I purchased it a few months ago. I own a Nikon 35mm 1.8, Tokina 100mm 2.8 macro, Sigma 10-20mm all of which are working properly, focusing perfectly. I picked up a used Sigma 70-200mm 2.8 EX DH APO Macro HSM II last night and have been having problems with it. The lens shoots sharp as a tack when I manual focus, but when I switch to AF every shot comes out slightly blurry.

I have tested the lens hand held, tripod mounted, etc etc etc with the same results....every shot is blurry when using AF. When I manual focus the camera to perfect (to my eye) focus, then half depress shutter to AF the camera takes the lens out of focus to the slightly blurry focus and locks in to "focus". I'm very new to the dslr scene, but I'm pretty sure this is a lens problem with this particular Sigma. Is there any way to correct this or is this something that a trip back to the manufacturer can correct?

I want to have all the facts before I decide what to do with the lens, whether I can correct this with in camera settings or return it to the person who I purchased it from, or send it out for repairs and ask the seller to pay for them. Any information you guys/gals could provide would be greatly appreciated.

Thanks in advance, Dennis
 
Small update.....forgot to mention, the lens is front focusing. I attempted to correct this within the camera using the AF fine tuning. There was no difference in point of focus clarity throughout the range of settings. The image was exactly the same front focusing from -20 to 0 fine tuned. Tested with tripod mount, remote shutter release.
 
Yes, it sounds like a problem specific to that lens. It is doubtful you can do anything about it yourself.

One issue with using 3rd party lenses is the possibility of forwards compatibility issues.

Camera makers do not provide proprietary information to 3rd party lens makers. The 3rd party lens makers have to 'reverse engineer' that proprietary info and usually wind up with some gaps, which may be why using the D7000's focus fine tuning didn't have any effect.
 
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I think your best option is to contact Sigma and see if the lens can be recalibrated. I'm not sure if the lens you're using is one of the ones affected, but I've heard of several Sigma lenses that simply had poor quality control regarding autofocus.

It may be a relatively inexpensive or free repair.
 
Yes, it sounds like a problem specific to that lens. It is doubtful you can do anything about it yourself.

One issue with using 3rd party lenses is the possibility of forwards compatibility issues.

Camera makes do not provide proprietary information to 3rd party lens makers. The 3rd party lens makers have to 'reverse engineer' that proprietary info and usually wind up with some gaps, which may be why using the D7000's focus fine tuning didn't have any effect.

Thanks, I was wondering why the AF fine adjustments were doing absolutely nothing.


I think your best option is to contact Sigma and see if the lens can be recalibrated. I'm not sure if the lens you're using is one of the ones affected, but I've heard of several Sigma lenses that simply had poor quality control regarding autofocus.

It may be a relatively inexpensive or free repair.

I took your advice and drove out to Sigma this afternoon. They took my D7000 and the lens in for recalibration and 2 hours later....presto, problem fixed! The lens was still under warranty, so no charge as well. Thanks again for the suggestions.
 
Your fortunate. Sigma's lens warranty isn't transferable. Technically, you had no warranty because you were not the original owner.

Plus. it's always handy when you are right there on Long Island in easy driving distance of the corporate headquarters.
 
Your fortunate. Sigma's lens warranty isn't transferable. Technically, you had no warranty because you were not the original owner.

Plus. it's always handy when you are right there on Long Island in easy driving distance of the corporate headquarters.

Who says I'm not the original owner ;) The warranty card was blank and the lens was never registered with Sigma. As far as they're concerned going forward I'm the original owner now! I have the worst luck in the world, this is the first break I've caught in like 10 years. (as I knock the camera and lens off my desk and break both of them, i see that coming)
 

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